The present invention relates, in general, to pneumatically driven electric power generators and, more particularly, the instant invention relates to electric power generators for railway vehicles.
The classical railroad airbrake system which was derived from the Westinghouse airbrake has, in recent years, been augmented by introducing electrical controls, while maintaining the reliability inherent in the fundamental pneumatic portions of the classical airbrake system. These electrical control systems generally require batteries in the individual railway vehicles and it is desirable to provide a generator on each car to maintain the batteries in a charged condition. For some proposed electrically controlled pneumatic systems, a power level as small as one Watt may be sufficient. Prior art generators for railway vehicles generally employ rotary mechanical power obtained from an axle of the railway vehicle. A generator may be positioned near an axle and receive power through a V-belt or flat belt drive from a pulley on the axle. Some generators are mounted coaxially with the axle over the end of the axle bearing. Other generators use gears and clutches to extract rotary mechanical power from the axle. These generators are usually much larger, complex and expensive and are heavier than is necessary for generating a small amount of electrical power.
The invention is a pneumatically driven electric power generator which includes a cylinder having a first end connectable through an inlet flowpath to an air supply passage containing air at a positive pressure, a second end of the cylinder being open. It also has a piston having a magnetic moment, the piston being positionable in a first location wherein at least a first portion of the piston is disposed within the cylinder. Sealing means are disposed on the outer surface of the first portion of the piston or the inner surface of the cylinder to prevent loss of air between the piston and the cylinder and permit air pressure in the cylinder to increase when the first portion of the piston is disposed within the cylinder. The piston is also positionable in a second location wherein the first portion of the piston is outside of the cylinder so that clearance is provided between the piston and the cylinder so that air may exhaust from the cylinder. Means are provided for biasing the piston from the second position toward the first position so that after the cylinder has exhausted, the piston moves to the first position, whereby the piston oscillates, moving back and forth between the first position and the second position, driven by air supplied through the air supply passage to the cylinder. The invention also has at least one electric coil placed to enclose changing magnetic flux caused by the magnetic moment associated with the piston whereby an emf is generated in the electric coil, so that an external circuit connected to the electric coil receives electric power from the electric coil.
In another aspect, the invention is a pneumatically driven electric power generator which includes a first cylinder having a first end connectable through a first inlet flowpath to an air supply passage, a second end of the first cylinder being open. It also has a second cylinder having a first end connectable through a second inlet flowpath to said air supply passage, a second end of the second cylinder being open. The invention includes a piston having a magnetic moment associated therewith, the piston having a first end portion and a second end portion. The piston is positionable in a first location wherein the first end portion of the piston is disposed within the first cylinder and the second end portion of the piston is disposed outside of the second cylinder. It is also positionable in a second location wherein the second end portion of the piston is disposed within the second cylinder and the first portion of the piston is outside of the first cylinder. When the piston is disposed in the first position, air pressure received in the first cylinder through the first inlet flowpath drives the piston toward the second position, whereupon the first cylinder exhausts. Likewise, when the piston is disposed in the second position, air pressure received in the second cylinder through the second inlet flowpath drives the piston toward the first position, whereupon the second cylinder exhausts, so that the piston oscillates. At least one electric coil is placed to enclose changing magnetic flux caused by the magnetic moment associated with the piston whereby an emf is generated in the coil, so that an external circuit connected to the coil receives electric power from the coil.
It is, therefore, one of the primary objects of the present invention to provide a simple and inexpensive generator for supplying electrical power for a railway vehicle.
Another object of the present invention is to provide a small and lightweight generator for supplying electrical power for a railway vehicle.
Still another object of the present invention is to provide an electric power generator for a railway vehicle which does not require gears and clutches to extract rotary mechanical power from an axle of the railway vehicle.
An additional object of the present invention is to provide an electric power generator for a railway vehicle which does not require a belt drive for extracting rotary mechanical power from an axle of the railway vehicle.
A further object of the present invention is to provide a small electric power generator employing a brake airline as an air supply and using so little air that even when such a generator is on all the railway vehicles in a long freight train, the air used does not seriously add to the airline leakage rate.
Yet another object of the present invention is to provide an electric power generator for a railway vehicle which does not need to be mounted on a truck of the railway vehicle.
Still another object of the present invention is to provide an electric power generator for a railway vehicle which may be mounted anywhere on the railway vehicle.
In addition to the various objects and advantages of the present invention which have been generally described above, there will be various other objects and advantages of the invention that will become more readily apparent to those persons who are skilled in the relevant art from the following more detailed description of such invention, particularly, when such detailed description is taken in conjunction with the attached drawing figures and with the appended claims.